phosphoactivate

The story

1. Proto-Indo-European*bʰeh₂-
2. Proto-Indo-European*bʰéh₂os
3. Proto-Hellenic*pʰáwos
4. Ancient Greekφᾰ́ος (phắos)
5. Ancient Greekφῶς (phôs)
6. Proto-Indo-European*bʰer-
7. Proto-Indo-European*bʰéreti
8. Proto-Hellenic*pʰérō
9. Ancient Greekφέρω (phérō)
10. Ancient Greekφωσφόρος (phōsphóros)
11. Latinphōsphorus
12. Englishphosphorus
13. Englishphospho-
14. Proto-Indo-European*h₂eǵ-
15. Proto-Indo-European*h₂éǵeti
16. Proto-Italic*agō
17. Latinagō
18. Ancient Greekἐνεργητικός (energētikós)
19. Latināctīvu
20. Old Frenchactif
21. Middle Englishactyf
22. Englishactive
23. Englishactivate
24. English todayphosphoactivate

From phospho- + activate.